Epidemiological data suggest that, especially among the aged, sleep complaints predict several percent of all deaths. Use of sleeping pills is associated with further increases in mortality. Nevertheless, we do not know the prevalence of objective sleep disorders among the elderly, the causal mechanisms of sleep disorders in mortality, or the balance of benefits and risks in long-term use of prescription hypnotics. We lack this crucial knowledge although 10-30% of our population complains of insomnia or uses prescription hypnotics. It has been difficult to study sleep problems scientifically due to a lack of convenient, inexpensive recording methods. This study will pioneer and evaluate a home and ambulatory diagnostic approach for sleep disorders among the elderly. Further, we will estimate the nature and prevalence of sleep disorders among the elderly in the San Diego Community. With the validation of home recording methods, the cost of scientifically diagnosing sleep disorders can be reduced by about 90%. Three home sleep recordings and one laboratory sleep polysomnogram will be made on each of 240 elderly volunteers. Reliability of measurement of sleep time and reliability of diagnosis will be evaluated between home and laboratory recordings and between sequential home recordings. Home recording techniques will be applied in future experiments to determine the true prevalence of sleep disorders, their role in population mortality, and the benefits and risks of hypnotic drugs.